Question

Which one of the following is not a quadratic equation? *


(x + 2)² = 2(x + 3)

x² + 3x = (–1) (1 – 3x)²

(x + 2) (x – 1) = x² – 2x – 3

x³ – x² + 2x + 1 = (x + 1)³

someone please ans

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Answer 1

${\huge{\boxed{\mathcal{\purple{Answer}}}}}$

You must know , that a quadratic equation is that equation in which the highest Power of the variable must be 2..

Let's check for all options..

Option 1

x² + 4 + 4x = 2x + 6

=> x² + 4 + 4x - 2x - 6 = 0

=> x² + 2x - 2 = 0

So, it is a quadratic equation...

Option 2

x² + 3x = (-1)(1 + 9x² - 6x)

=> x² + 3x = -1 -9x² + 6x

=> x² + 9x² + 3x - 6x + 1 = 0

=> 10x² - 3x + 1 = 0

So, it is also a quadratic equation

Option 3

(x + 2)(x - 1) = x² - 2x - 3

=> x² - x + 2x - 2 = x² - 2x - 3

=> x² + x - 2 = x² - 2x - 3

=> x² - x² + x + 2x -2 +3 = 0

=> 3x + 1 = 0

So, it is not a quadratic equation

Option 4

x³ - x² + 2x + 1 = x³ + 1 + 3x(x+1)

=> x³ - x² +2x + 1 = x³ + 1 + 3x² + 3x

=> x³ - x³ - x² - 3x² + 2x - 3x + 1 - 1 = 0

=> -4x² - x = 0

So, it is also a quadratic equation..

So, finally Option 3 is the correct answer